Instrument for recording inclination



April 25, 1933. w. l. MCLAUGHLIN Er AL 1,905,299

INSTRUMENT FOR RECORDING INCLINATION Filed Nov. 3, 1950 3 Sheets-Sheet lw. l. MCLAUGHLIN ET A| ,y 1,905,299

INSTRUMENT FOR RECORDING INCLINATION Filed Nov. 5, 195o s sheets-sheet 2April 25, 1933.

dnb@

April 25, 1933. w. l. MCLAUGHLIN Er AL y 1,905,299

INSTRUMENT FOR RECORDING INCLINATION Aso Patented Apr 25, 1933 UNITEDSTATES WILLIAM I. MCLAUG-HLIN, 0F IIEDMONT, AND RUPERT G. WEDEMEYER, OFPALO ALTO,

PATENT OFFIC CALIFORNIA; SAID WEDEMEYER ASSIGNOR TO STANDARD OIL COMPANYOF CALI- FORNIA, 0F SAN FRANCISCO, CALIFORNIA, A CORPORATION 0F DELAWAREINSTRUMENT FOR RECORDING INCLINATION Application led November 3, 1930.Serial No. 493,056.

This invention relates to an instrument for recording the inclination ofthe drill pipe in the drilling ofoil wells and more specifically relatesto an Ainstrument adapted to be mounted in the drill Collar or pipeduring the drilling operation and tobe actuated by the pressure of thedrilling fluid or mud to record the inclination of the drill pipe. 4

In the drilling of oil Wells the use of drill pipe and the forcing of adrilling fluid such as mud down through the drill pipe to wash out thecuttings is so common and so thoroughly understood by those .skilled inthe drilling art that further description 1s deemed unnecessary.

An instrument as described in these specifications and as illustrated inthe accompanying drawings, as will be appreciated by those skilled inthe art, is applicable for a great many different uses, but for thepurpose of illustration the invention, will be described and illustratedas adapted to oilI well surveying.

In drilling oil well bores, it is desirable to drill a straight holewhich will be perpendicular to the normal surface of the earth. However,in the course of drilling the well, the drilling tool is oftendeflected, or, as commonly termed, drifts from its true course. Thedriller can operate the drilling tool to bring the well bore back to itstrue course, providing he knows of approximately the locality'of thedr1ft. t is, therefore, the principal object of this invention toprovide an instrument which may be mounted in the drill pipe andarranged whereby the instrument may be actuated to record theinclination of the drill pipe where and when deemed necessary.

To withdraw the drill pipe requires considerable time and labor and is,therefore, eX- pensive and consequently the drill pipe, is run as longas possible before being withdrawn and it is, therefore, important toprovide an instrument which may be actuated any number of times to checkthe inclination of the drill pipe during a single run.

'It is a further object of this invention to provide an instrumentwhichmay be actuated any number of times during a single run of tige drillpipe to record the inclination thereo It is a further object of thisinvention to provide an instrument which when mounted in the drill pipewill not materially interfere with or stop the flow of drilling fluidpumped through the drill pipe.

It is a further object. of this invention to provide an instrument whichwill permit the normal filling anddraining of the drillI pipe during therunning-in and withdrawal of ,the drill pipe.

.Itis a. further object 'of this invention to provide an investmentwhich will actuated.

permit the running-in and withdrawal of the drillv pipe without causingthe instrument to be It isa. further object of this invention to l andcombinations of parts to be describedv hereinafter, all of whichcontribute to produce an efiicient and easily operated instrument forrecording the inclination of the drill pipe. A preferred embodiment ofthe invention is described in the following specifications andillustrated in the drawings, while the full scope of the invention ispointed out in the appended claims.

In the drawings:

Figure l is a longitudinal view of the invention illustrating theposition of the` operating parts of the instrument during the time thedrilling iiuid is being pumped through the drill pipe, and furtherillustrating the recording disc moved out of engagement with theplumb-bob.

Figure 2 is a view similar to Figure l, illustrating the position of theoperating parts of the instrument when the drilling fluid pumps havebeen stopped and the pressure thereof dissipated from the drill pipe andalso illustrating the recording disc moved int) recording engagementwith the plumbbo Figure 3 is a plan view, taken substantially on line3-3 of Figure 2, looking in the direction of the arrows.

Figure 4 is a sectional view, taken substantially on line 4 4 of Figurel, looking in the direction of the arrows.

Figure 5 is a longitudinal sectional view of the instrument illustratinga modified form of the actuated means and illustrating the position ofthe parts when the drilling fluid pumps have just been started, causingthe parts to be moved downward and also illustrates the plumb-bob heldout of engagement with the recording disc.

Figure 6 is a fragmental view of Figure 5 illustrating the relativeposition of the parts when the drilling fluid pumps have )ust beenstopped and therefore the parts are moving upward causing the bob to beforced into recording engagement with the recording disc.

Figure 7 is a longitudinal sectional view of the instrument illustratinga further modiiied form of the actuating means and illustrating therelative position of the parts when the drilling fluid pumps are at restand further illustrating the bob held out of engagement with therecording disc.

Figure 8 is a fra mental view of Figure 7, illustrating in bro en linesthe relative positions of the parts when the drilling fluid pumps areoperating, and further illustrating in full lines the bob in recordingengagement with the recording disc resulting from the return of theoperating parts to theirZ normal position, as illustrated in Figure Inthe preferred embodiment of the invention, as illustrated in thedrawings, and especially in Figures 1 to 4, inclusive, a suitablesupporting tube 1 is provided. The supporting tube 1 may be of anysuitable sizefor retaining the instrument and aligning the instrumentwithin the inner bore of the drill pipe or collar, (not shown). Forconvenience and as illustrated in the drawings, the instrument properhas been located oil' center of the supporting tube 1 but it is alsopractical to place the instrument in the center thereof.l Suitablysecured to the upper end of the tube 1 is a valve block 2 having abypass opening 3 and a large opening 4. Pivotally mounted upon the uppersurface of the valve block 2 is a bypass valve 5 arranged in position toclose the bypass opening 3. A cylinder 6 may be suitably secured to orformed integral with the valve block 2 and in alignment with the largeopening 4, and is provided with ports 7 and a guide slot 8. A cylinderhead 9 is secured to the lower end of the cylinder 6 and is providedwith a piston rod guide bore 10, a large passage 11 and a relativelysmall passage 12 and suitably secured to the lower end of cylinder head9 is an encasing and spacing tube 13. Suitably. secured to the lower endof encasing tube 13 is a bearing block 14 having a plunger guide bore15, two slnall pressure equalizing passages 16 and two projections 17. Aplumb-bob 18 is pivotally suspended on a ball and socket mounting 19which is secured tothe bearing block projections 17. The plumb-bob 18 isenclosed by means of tube 20 which forms a tight joint with bearingblock 14 and is sealed gti its lower end by means of a removable plugThe parts just described in reality constitute the supporting structureof the instrument and as arranged provide a structure by which the moredelicate parts of the instrument may be protected by filling thesupporting structure with water, oil or grease so that these parts willnot be hindered in their proper functioning by the heavy drilling mud.The supporting structure also provides for equalizing the pressure inthe instrument with the pressure ofthe drilling fluid, the pressureequalizing passages are so arranged that the pressure is equalized fromone chamber to the next serially so as to further safeguard the properfunctioning of the plumb-bob. The passage 11 is larger in volume thanthe volume displaced by the action of the piston rod 25 later to bedescribed, in moving into and out of the spring chamber so that nodrilling mud will be forced into the spring chamber.

The operating parts include a piston 22 slidably mounted in cylinder 6and is provided with a rod support 23 which projects through thecylinder guide slot 8 and is provided with a-n upwardly extending rod 24adapted, when the piston 22 is at the upper end of the stroke, to engageand hold open the by-pass valve 5 which position is illustrated inFigure 2.

A piston rod 25 is operatively connected withV piston 22 and extendsthrough guide bore 10 of cylinder head 9. A plunger 26, in alignmentwith the piston rod 25, is guided in bore 15 of bearing block 14 and atits upper end is provided with a tube 27 into which th lower end ofpiston rod 25 is slidably fitte As piston rod 25 moves relative to tube27 it is necessary to vent the tube and for this purpose any suitablemeans may be used, such as vent holes 28. Connected to the lower end ofplunger 26 is yoke 29 which may be guided by the two projections 17 ofbearing block 14. rl`he extent of travel of yoke 29 is limited betweenblock 14 and the plumb-bob mounting 19.

Secured to yoke 29 is the operating cylinder 30 which is slidablymounted in the plumb bob encasing tube 20. There is also slidablymounted in the plumb-bob encasing tube 20 a plunger 31 which is guidedby a plunger rod 32 and is yieldably held in engagement with the lowerend of operating cylinder 30 by means of spring 33 which is mountedbetween the plunger 31 and the removableplug 21.

Suitably mounted upon plunger 31 is a recording disc 34 of suitablematerial such as wood, a soft white metal or brass, on whlch are scribedcircles so that the degree from the vertical may be read. Suitable meansare employed for normally and yieldingly retaining the ,operating partsof the instrument in the position shown in Figure 2. The first portionvof these means includes a primary spring 35, asecondary spring 36, anintermediate washer 37 and a washer or collar 38 which is suitablysecured on the piston rod 25. The washer or collar 38maybe provided witha sleeve preferably formed integral therewith and arranged tosurroundspring 35. .The sleeve formed upon the collar 38 may be dispensed withand a pin or other means may be positioned in or secured to the pistonrod 25 to eontrOl the amount of travel of piston rod 25 as illustratedin Figures 5 and 6. By this arrangement of parts, the piston 22 ismaintained in the position illustrated in Figure 2.

The primary spring is adjusted t0 eni able the piston 22, when the pumpis started,

to move a sufiiocient distance to withdraw rod 24 from holding bypassvalve 5 open and to thus permit the bypass valve 5 to close, so that theentire pressure of the drilling fluid or mud will be exerted againstpiston 22 which will cause piston 22 to exert sufficient force to movedownward against the forces of springs 35 and 36, and until a sufficientportion of the port 7 is exposed to take carel of the pumped fluid.

The second portion of these means includes the spring 39 surrounding theplunger 26 and positioned between slidable washer 37 and a washer orcollar 40 suitably secured on plunger 26. When the piston rod 25compresses spring 36 spring 39 is likewise compressed until finallyspring 39 overcomes the force exerted by spring 33 to shift therecording disc 34 away from the point of the plumbbob 18. This positionof parts is illustrated in Figure 1. When the pumps are stopped, thepressure of the drilling fluid or mud is dissipated and the forceexerted by the springs 35, 36, and 39 is sufficient to return piston 22to its initial position and to cause piston 22 by means of rod 24 toopen the ypass valve 5 and also enables spring 33 to again force therecording disc 34 in recording engagement with the point of bob 18.

The operation of the instrument is as.

Vplumb-bob 18. As soon as the drill pipe has ,been run-in the drillingoperation is commenced. The pumps are turned on to pump drilling-fluidor mud through the drill pipe to the drilling tool. This mud passesthrough the instrument between the instrument proper and the inside oftube 1. The pressure of the pumped drilling fluid will be sufficient toforce piston 22 to lower, thus lowering rod 24 until the bypass platevalve l 5 is closed so that` the entire pressure of the drilling mudwill be exertedjagainst piston 22 thus causing piston 22 to move stillfurther until sufficient, area of port 7 is uncovered to permit thepumped fluid to discharge into the inside of tube 1.

The lowering of piston 22 transmits motion through piston rod 25, spring39 to plunger 26, yoke 29, operating t'ube 30 which in turn forcesplunger 31 down against the action of spring 33 and also plunger 31carries the recording disc 34 out Ofengagement with bob 18. The bob 18is now released so that it may swing freely. When itis desired to take areading, to determine whether the drilling operation' has drifted orinclined from its true course, the rotation of the drill pipe is stoppedand the pumps continued in action to maintain the bob 18 free from therecording disc 34 until the bob has had suflicient time to settle into avertical plane. The pumps are then stopped to allowl piston 2 2 toreturn to its initial position, as shown in Figure 2, to again permltspring 33 to force plunger 31 and disc 34 into recording engagementwith' lumb-bob 18.

The dril string may now be removed from the well bore and by referringtothe recording disc 34 the driller can observe whether the well isbeing drilled on its true course, or whetherthe drilling tool has beendeflected or drifted from its true course. Should the driller desire tocontinue drilling. after taking the first reading the drilling isresumed and the pumps are .again started as before described.

As soon as the pumps are started plunger 22 is again forced downward andthrough the mechanism already described forces thev recording disc awayfrom bob 18. A second reading may be taken by again stopping thedrilling operation, permitting the bob to come to rest, and thenstopping the pump as before described, and upon completion of thereading, the drilling may be again resumed.

When it is necessary to raise the drill pipe 5 to change the tool, a newrecording disc 34 can be inserted in place of the old one. The readingson the old disc may bc entered in the log and the disc filed away forfuture reference.

In the modified form of the invention illustrated in Figures 5 and 6,there is suitably secured adjacent the upper end of supporting tube 51 avalve block 52 having the bypass opening 53 and opening 54, andpivotally mounted upon the upper surface thereof is `bypass valve 55positioned to close opening 53. A cylinder 56 is suitably secured inopening 54 and is provided with ports 57 and guide slot 58. The cylinderhead 59 is secured to the lower end of cylinder 56 and is provided witha piston rod guide bore 6() and passages 61 and 62. A spacing tube 63.is secured to the lower end of head 59 and to the lower end thereof. issecured bearing block 64 having plunger rod guide bore 65 and twov smallpressure equalizing passages 66.

Secured to the lower end thereof is the plumb-bob enclosing tube 67which is tightly sealed at its lower end by the removable plug 68. Arecording disc 69 made of wood, brass or'any other suitable material, issecurely held adjacent the lower end of the plumbbob enclosing tube 67by any suitable means such as in the present instance by the removableplug 68. The recording disc 69 may be inscribed with concentric circlesindicating degrees from the vertical. Suitably mounted in spacing tube`63 adjacent bearing block 64 is the guide block 70 which is providedwith a piston rod guide bore 71, a pressure equalizing tube 72, anenlarged central bore 73, a longitudinal slot 74, and extendingtransversely of slot 74 is the cam lever pivot pin 75 and the bobactuating lever pivot pin 76.

Having described the stationary elements which in reality form theframework of the instrument proper, the operating elements will now bedescribed in relation thereto:

Slidably mounted in cylinder 56 is piston 77 and to enable the pist-onto -actuate'the bypass valve 55 a rod 78 is suitably mounted upon piston77 by rodsupport 79. Operatively connected to pist-on 77 1s a piston rod80 whichl passes through the guide bores 60 and 71 and has positionedupon its lower end an operating cam surface 8l. To yieldably maintainpiston77 in the upper end of cvlinder 56 in position so that rod 78holds open thebypass 'valve 55, two springs are provided. The )rimaryspring 82. is of less strength than t e secondary sprlng 83 to ermit arelatively light pressure of the drill- 55 lng Huid to actuate piston 77to withdraw rod 78 so that bypass valve 55 .may close passage 53 todivert the entire volume and pressure of the pumped drilling fluid toact upon piston 77 to force piston 77 downward against the action of thesecondary srng 83 a suicient distance to uncoversu cient area of ports57 and slot 58 to permit the pumped drilling fluid to pass through theinstrument.

To provide for the action of springs 82 and 83 just described, anysuitable arrangement may be used, in the present instance, spring 83 ismounted around piston rod 8O and abuts at one end against guide block 70and at the other end against the slidable washer 84 limited in its moveby any suitable means, such as pin 85.

As will be noted in Figure 6, pin 85 is not in engagement with washer 84but upon the downward movement of piston 80, due to pressure acting uponpiston 77, pin 85 is brought into engagement with washer 84 and uponfurther downward travel of piston rod 80 compression of spring 83 takesplace. The primary spring 82 1s positioned surrounding ,piston rod 80and acting between washer 84 and washer or collar 86 suitably secured tothe piston rod 80 as in this instance by pin 87.

Then the piston rod 80 is forced downward cam surface 81l engages thecam surface of cam lever 88. As is clearly shown in Figure 5 a furthermovement of cam 81 4forces cam lever to rotate about its pivot 75 in aclockwise direction until cam 81 has passed by. A cam lever spring 89returns lever 88 to its normal position. When the pressure of thedrilling fluid is released, piston 77 piston rod 80 and cam 81 are movedupward due to the tension of springs 82 and 83. The cam surface 81 inits upward course, again engages'cam lever 88, but this time, as will benoted from Figure 6, cam lever 88 is swung in a counterclockwisedirection` causing one arm of lever 88 to engage arm 90 of bell cranklever 91 which is pivoted upon pin 7 6. Arm 92 of lever 91 extends inposition to engage the plumb-bob 'actuating plunger 93. The plunger 93extends through and is guided in bore of bearing clock 64 and upon'thelower end thereof is a pivotal mounting, such as the ball and socketjoint 94 of. plumb-bob 95.

er 93, is a collar orwasher 96 acted upon by spring 97, which normallyyieldably holds bob 95 out of engagement with the recording disc 69.When plunger 93 is engaged and 'forced downward by arm 92 of lever 90,

spring 97 is compressed and bob 95 is forced into recording engagementwith disc 69. The positiop of the parts just described is illustrated inFigure 6. When cam 81 passes above lever, 88. spring 89 returns lever 88to its normal position and likewise spring 97 returns lever 91 to itsnormal position and Secured, adjacent the upper end of plungwith disc69.

Inl the form of the invention just described, it will be seen that thebob is only momentarily forced into recording engagement with therecording disc and this action takes place only after the pumps havebeen started and then shut off. Like in the previous form of theinvention, any number of readings may be taken where and when deemednecessary by the driller.

Like in the previous form of the invention, it is desirable to lill theplumb-bob chamber 98 the central bore 73 and chamber 99, also passages61, 62, 72 and 66 with Water, oil, grease or other suitable Huid, forkeeping the mechanism and chambers free from the drilling Huid or mudand to permit 'the equalization of pressure inslde and out,

passage 62 should be of greater volume than that volume displaced bypiston rod 80 so as to prevent the mud from Working into chamber 99.

In the modilication of the invention illustrated in Figures 7 and8, itwill be noted that the instrument proper is mounted substantiallyconcentric with the supporting tube 201, whereas cylinder 202 andpassage 203 are positioned as in the previous gures. A piston rod 204transmits the motion of piston 205 to crosshead 206, through crosshead206 to valve rod 207 positioned to actuate the bypass valve 208 and alsothrough crosshead to plunger 209.

Suitably mounted in supporting tube 201 is the supporting member 210having one or more fluid passages 211, a plunger guide bore 212 and apressure equalizing passage 213. The supporting member 210 is alsoprovided with a section of reduced diameter to which tube 214 issuitably secured. A guide block 215 is secured to the lower end of tube214 and is provided with a plunger rod guide bore 216 and one or morepressure equalizing passages 217. A second tube 218 is suitably securedto the lower end of guide block 215 and secured to tbe lower end of saidtube is bearing block 219 having a plumb-bob plunger and guide bore 220and the pressure equalizing passage 221. A plumb-bob enclosing tube 222is secured to the lower end of bearing block 219 and is sealed at itsopposite end by the removable plug 223. A recording disc 224 of wood`brass, or other suitable material. is irmlv held in tube 222 by means ofplug 223 or other suitable means.

Plunger 209 extends through the guide bores 212 and 216 of members 210and 215` respectively`l and is yieldingly maintained in its upperposition, as illustrated in Figure 7. by substantially the samearrangement of springs as shown in the previous figures. llpon the lowerend of plunger 209 is mounted block 225 to which is suitably secured aspring latch 226 comprising a flat spring 227 and the latch member 228.Secured to'tube 218 is a guide member 229 for controlling the action oflatch member 228. Pivotally mounted in tube 218 is lever 230 having oneend positioned to be engaged and rotated inA a counterclockwisedirection by latch member 228 upon its upward travel, as illustrated inFigure 8, and positioned whereby its opposite end engages and actuatesthe plumbbob plunger 231 when rotated by latch member, as above stated.The plumb-bob plunger 231 is guided in and extends through bearing block219 and is provided at its lower end with a suitable pivotal, or balland socket, -mounting 232 for the plumb-bob 233. The bob 233 is normallyheld outl of engagement with the recording disc 224 by means of spring234 positioned between bearing block 219 and washer 235 suitably securedadjacent the upper end of plunger 231.

In operation, when the pumps are started spring latch is lowered to theposition indicated in broken lines in Figure 8, through the elementsalready described. When the pumps are shut olf and the pressuredissipated, the spring latch 226 moves upward, latch member 228 engageslever 230, as illustratcd in Figure 8 in full lines.

Lever 230 is rotated counterclockwise and due to its operative relationwith the bob plunger 231 the bob 233 is forced into engagement with therecording disc 224 thus recording the inclination of the drill pipe.Upon further movement upward of spring latch 226 the inclined surface236 of latch member 2,28l contacts with a similar inclined surface 237of guide member 229 to force latch member 228 laterally to disengage itfrom lever 230.

The instrument may be caused to actuate any number of times during thedrilling o eration by stopping the rotationy of the dr1ll vpipe topermit bob 233 to seek the true vertical .plane and then by stopping thedrilling Huid pumps and as the pressure of the drilling uid dissipatesthe bob is actuated to record upon the disc the inclination of theinstrument and thus the inclination of the drill pipe from its truecourse.

The structure of the instrument provides three separate chambers, namelythe bob chamber 238, actuating mechanism chamber 239 and spring chamber240. Communicating between bob chamber 238 and actuating mechanismchamber 239 is the pressure equalizing passage 221 and between chamber239 and the spring chamber 240 there are one or more pressure equalizingpassages 217, and finally passage 213 equalizes the pressure in chamber240 with the pressure surrounding the exterior of the instrument.

Before the instrument is mounted in the drill collar or pipe thechambers and equalizing passages are all filled with water, oil or otherfluid to prevent the intrusion of the drilling Huid into the instrument.Passage 213 should be of greater volume than that volume displaced bythe plunger 212 when moved in or out of the instrument proper.

Having fully described my invention, it is to be understood that I donot wish to be limited tothe details herein set forth, but my inventionis of the full scope of the appended claims:

I claim:

1. An instrument for measurin inclination includingV the combination o apivotally mounted plumb-bob, a recording disc, a piston slidable touncover a Huid passage, a spring means opposed to said piston, and meansassociated with said piston for yieldingly forcing said bob and disc toand fro recording engagement.

2. An instrument for measuring inclination including the combination ofa pivotally mounted plumb-bob, a recording disc, a bypass means, apiston slidable to uncover a fiuid discharge passage and arranged toactuate said bypass means, a spring means opposed to said piston, andmeans associated With said piston for yieldingly forcing said bob anddisc to and from recording engagement.

3. An instrument for measuring inclination including the combination ofa pivotally mounted plumb-bob, a recording disc, a bypass valve, acylinder having a discharge port, a piston slidably mounted in saidcylinder and arranged to open and close said discharge portand operativeto actuate said bypass valve, a differential spring means opposed tosaid piston whereby said piston may be moved by a relatively lowpressure to close said bypass valve and whereby said piston may be moveda further distance by a higher pressure to uncover said cylinderdischarge port, and means associated with said piston for yieldinglyforcing said bob and disc to and from recording engagement.

4. An instrument for measuring inclination including the combination ofa pivotally mounted plumb-bob, a recording disc, a cylinder` having abypass means and adischarge port, a piston slidably mounted in saidcylinder and arranged to actuate said bypass means and to open or closesaid discharge port, a primary spring means opposed to said piston andarranged to permit a relatively low pressure to move said piston toclose said bypass means, a secondary spring means opposed to said pistonand arranged to permit a greater pressure to further move said piston toopen said discharge port, and means associated with said piston foryieldingly forcing said bob and disc to and from recording engagement.

5. In an instrument for measuring inclination, a fluid seal thereforincluding the combination of a supporting structure having a pluralityof chambers adapted to be filled bination of a supporting structurehaving' a plurality of chambers adapted to be filled with a suitablefluid and having pressureV equalizing ports serially connecting saidchambers With the exterior thereof and whereby the volume of the portcommunicating with the exterior is of greater capacity than the volumeof fluid displaced in said chamber during the operation of theinstrument.

7. An instrument for measuring inclination, including the combination ofa supporting structure having a plurality of chambers adapted to befilled with a suitable fluid and having pressure equalizing portsserially connecting said chambers with the exterior thereof, a plumb-bobpivotally mountedin one of said chambers, a recording disc, and meansresponsive to changes in fluid pressure for forcing said bob and disc toand from recording engagement.

8. An instrument for measuring inclination including the combination ofa supporting structure having a plurality of chambers adapted to befilled with a suitable fluid and having pressure equalizing portsserially connecting said chambers with the exterior thereof, a plumb-bobpivotally mounted in one of said chambers, a record disc, a cylinderformed in said supporting structure and having a bypass means and adischarge port, a piston slidably mounted in said cylinder and arrangedto actuate said bypass means and to open or closesaid discharge port, aspring means mounted in serial chambers and opposed `to said piston, andmeans extending through said chambers associated with said piston foryieldingly forcing said bob and disc to and from recording engagement.

9. An instrument for measuring inclination including the combination ofa supporting structurehaving a plurality of chambers adapted to befilled with a suitable iuid and` having pressure equalizing portsserially connecting said chambers with the exterior thereof, a plumb-bobpivotally mounted in one of said chambers, a recording disc associatedtherewith, a cylinder formed in said supporting structure and having abypass means and a discharge port, a piston slidably mounted in saidcylinder and arranged to actuate said bypass means and to open or closesaid discharge port, a primary spring means opposed to said piston andarranged to permit a relatively low pressure to move said piston toclose said bypass means, a secondary spring means also opposed to saidpiston and arranged to permit a further movement of said piston when agreater pressure is exerted thereagainst to open said discharge port,and means associated with said piston for yieldingly forcing said boband disc to and from recording engagement.

10. An instrument for measuring inclination including the combination ofa piston slidable to uncover fluid passages, a spring means opposed tosaid piston, a pivotally mounted plumb-bob, a recording disc, and meansoperatively connecting said piston and said dis 11. An inclinationrecording instrument including the combination of a pivotally mountedplumb-bob, a recording'disc, means for yieldingly holding said bob anddisc in recording engagement, and means actuated by fluid pressure forreleasing said bob and disc from recording engagement.

12. An inclination recording instrument including the combination of apivotally mounted plumb-bob, a. recording disc, means to yieldingly holdsaid bob and disc in recording engagement, and meansroperated by fluidpressure to actuate said yieldable holding means to release said bob anddisc from recording engagement. l

13. An inclination recording instrument including the combination of apivotally mounted plumb-bob, a recording disc, means for yieldinglyholding said bob and disc in recording engagement, and means responsiv'eto a predetermined fluid pressure for releasing said bob and disc fromrecording engagement.

14. An inclination recording instrument includingthe combination of apivotally mounted plumb-bob, a recording disc, a spring to yieldinglyhold said bob and disc 1n recording engagement, a piston actuated bypressure fluid to release and hold released said bob and disc fromrecording enga-gement.

15. In an instrument for recording inclination, an operating mechanismfor actuating a recording disc to and from recording engagement with apivotally suspended plumb-bob including the combination of a pistonslidably mounted in the instrument, a piston rod associated with saidpiston, a' first spring means associated with said piston rod, arecording disc supporting means, and a. second spring means operativelyarranged between said piston rod and said disc supporting means.

16. In an instrument for recording inclination, an operatingmechanismfor actuating a recording disc to and from recording engagementwith a pivotally suspended plumb-bob including the combination of apiston slidably mounted in the instrument, a piston rod associated withsaid piston, a first spring means associated with said piston rod, and asecond spring means operatively arranged between said piston rod andsaid disc supporting means, and a third spring means for yieldinglyurging the recording disc into engagement with the plumb-bob.

17. An inclination recording instrument including the combination of aplumb-bob chamber filled with a suitable fluid, a pressure equalizingchamber likewisefilled with a suitable fluid, a pressure equalizingpassage serially connecting said chambers with the exterior thereof, aplumb-bob suitably mounted in said bob chamber, a recording disc alsosuitably moiuited in said bob chau1- ber, means for yieldingly holdingsaid bob and disc in recording engagement, and means fluid pressure toactuate said yieldable holding means for releasing said bob and discfrom recording engagement.

19. An inclination recording instrument including the combination` of apivotally mounted plumb-bob, a recording discassociated therewith,holding said bob and disc apart, and means actuated upon the release ofthe fluid pressure forforcing said bob and disc into recordinvengagement.

20. fn an instrument for recording'linclination adapted to be actuated`responsive to changes in fluid pressure comprising the combination of asupporting structure, a cylinder formed therein and having a bypassmeans and a fluid discharge means, a piston slidably mounted in saidcylinder and arranged to actuate said bypass means and to open or closesaid discharge means, a spring means operatively opposed to said piston,a recording disc suitably supported in said structure, a plumb-bobvpivotally mounted within said structure and associated with said disc,means for yieldably holding said bob out of recording engagement withsaid disc, a bob actuating means operatively associated with said pistonand arranged as said piston returns to its uppermost position to engageand actuate said bob holding means to force said bob into recordingengagement with said disc and upon further upward movement of saidpiston to automatically disengage from said bob holdmg means.

21. In an instrument for recording inclination an operating mechanismfor actuating a plumb-bob to and from recording engagement with arecording disc including means for yieldingly the combination of apiston slidably mounted in the instrument, a piston rod associated withsaid piston and having a head, a spring means associated with saidpiston rod, a first lever means positioned to be engaged and rotated bysaid piston rod head, a second spring means arranged to yieldably retainsaid first lever means in operative position, a second lever meanspositioned to be engaged and rotated by said first lever means when saidfirst lever means rotates in one direction, a plumb-bob supporting meanspositioned to be engaged and operated by said second le- `ver means, athird spring means arranged to yieldingly retain said bob supportingmeans inoperative engagement with said second lever means.

22. In an instrument for recording inclination including the combinationof a suitable supporting structure having a plurality of chambersadapted to be filled With'a suit-v able fiuid1 and having pressureequalizing ports serially connecting said chambers with the exteriorthereof, a cylinder formed in said structure and having a bypass meansand a discharge port, a piston slidably mounted in said cylinder andarranged to actuate said bypass means and to open or close saiddischarge port, a piston rod associated with said piston and having ahead,

a spring means mounted in the upper of said chambers associated withsaid piston rod, a first lever means operatively mounted in theintermediate of said chambers positioned to be engaged and rotated bysaid piston rod head,'a second sprin means mounted in the upper of saidcham ers arranged to yield- 'ingly retain said first lever means inoperative-position, asecond lever means operatively mounted'in theintermediate of said chambers positioned to be engaged and rotated bysaid first lever means when said first lever means rotates in onedirection, a plumbbob supporting means positioned to be engaged andoperated by said second lever means, a third spring means arranged toyieldingly retain said bob supporting means in operative engagement withsaid second lever means, a .plumb-bob pivotally suspended from said bobsupporting means in the lowermost of said chambers, and a recording discmounted in said lowermost chamber Within the operating range of saidplumbbob.

23. In an instrument for recording inclination including the combinationof a suitable supporting structure having a pluralityvof chambersadapted to be filled with a suitable fluid and having pressureequalizing ports serially connecting said chambers with the exteriorthereof, a cylinder formed in said structure and having a bypass meansand a discharge port, a piston slidably mounted in said cylinder andarranged to actuate said bypass means and to open or close saiddischarge port, a piston rod associated with said piston and having aspring latch, a spring means mounted in the upper of said chambers andassociated with said piston rod, a lever means operatively mounted inthe intermediate of said chambers and positioned to be engaged androtated by said spring'latch, a plumb-bob supporting means positioned tobe engaged and operated by said lever means, a second spring meansarranged to yieldingly vretain said bob supporting means in elevatedposition, a plumbbob pivotally suspended from said bob sup- 'portingmeans in the lowermost of said chambers, and recording disc mounted insaid lowermost chamber within the operating range of said plumb-bob.

24. In an instrument for recording inclination an operating mechanismfor actuating a plumb-bob to and from recording engagement with arecording disc including the combination of a piston slidably mounted inthe instrument, a piston rod associated with said piston and having aspring latch, a spring means associated with said piston rod. a levermeans positioned to be engaged and rotated by said spring latch, aplumb-bob supporting means positioned to -be engaged and operated bysaid lever means, and a second spring means arranged to yieldinglyretain said bob supporting means in elevated position.

25. In an instrument for recording inclination a bypass means includingthe combination of a supporting structure having a cylinder and a bypassport, a piston slidably mounted in said cylinder, a valve meansoperatively arranged to close said bypass port, and means. associatedwith said piston for actuating said valve means.

26. An instrument or measuring inclinations including the combination ofapiston slidable to uncover fiuid passages, a spring means opposed tosaid piston, a pivotally mounted plumb-bob, a recording disc, and meansoperatively connecting said piston and said bob.

27. In an instrument for recording inclination including the combinationof a valve means responsive to fiuid pressure, an enclosing structure, aplumb-bob pivotally mounted therein, a recording disc slidably mountedin said structure, means for resiliently urging said disc intoengagement with said bob, and means operatively connecting said valvemeans and said disc, and arranged to actuate said recording disc to andfrom recording engagement.

Signed at San Francisco this 29th day of October, 1930.

WILLIAM I. McLAUGI-ILIN. RUPERT G. WEDEMEYER.

